(a) Field of the Invention
The invention is related to an illuminating device to disclose an illuminating device which is capable of promoting white light color rendering.
(b) Description of the Prior Art
FIG. 1 is a cure diagram of natural sun light (natural white light), the light wavelength in said Fig. is between 360˜750 nm.
In order to manufacture a white light illuminating device with wavelength near natural sunlight (white light), the Taiwan patent no. 383508 “illuminating device and display device” disclosed that a blue light emitter diode is used as the blue light source to be triggered by a fluorescent body to emit a light of a wavelength different from blue light, and said light of different wavelength is mixed with the untriggered blue light to obtain the white light, whereby comparing the spectrum curve S1 (as shown in FIG. 2) of said white light with the curve of natural white light (sunlight) in FIG. 1, it is known that the deviation between said two curves is quite large which is mainly due to the white light defined by mixing the longer wavelength light from the fluorescent body triggered by blue light and the untriggered blue light obviously has a poor color rendering in comparison with natural sunlight, wherein said color rendering is between 40˜80.
Similarly, as white light emitter diode is not used, the embodiment by the red, green or blue light emitter diode, or by the combination of UV light emitter diode and fluorescent body is employed for resolution, such as that it is commonly seen on the street to add red fluorescent bodies for promoting the color renderingness, however most red florescent bodies contain sulfides which may corrode chips or sealing material after wetted by adsorption to cause fast decay of lightness and reliability problems for the whole light emitter diode. Further since human eyes have poorer sensitivity for red light wavelength region, the color renderness can be promoted by transforming more blue light energy of said light emitter diode to red light, however the lightness will go down by 30˜50% at present to have a poorer lighting efficiency.